The invention concerns an NMR (=nuclear magnetic resonance) spectrometer comprising a magnet configuration with a substantially vertically aligned elongated upper opening for receiving an elongated NMR sample extending along a sample axis, in particular, in a sample vial, with a measurement volume, in which, while an NMR measurement is being performed, the elongated NMR sample is positioned in a measuring position with a vertically aligned sample axis, and with a sample changer with at least one cylindrical sample holder for receiving the NMR sample at a loading position and for transferring the NMR sample into the measurement volume at a transfer position
Such an NMR spectrometer with a sample changing facility to be loaded vertically from above is described, for example, in DE 37 29 819 or in U.S. Pat. No. 5,534,780.
Spectroscopic techniques are commonly used in instrumental analysis to examine the chemical composition of samples. To measure a sample in NMR spectroscopy, for example, a sample is placed in a very strong static magnetic field and radio frequency (=RF) pulses are irradiated into the sample. The response of the sample to the RF pulses is measured. The static magnetic field is generated by the superconducting magnet coils; in modern high-resolution NMR spectrometers, the magnet coils are cooled with liquid helium in a cryostat. Such NMR spectrometers are more than one meter in height and are not suitable for use as table-top devices.
Various sample changers for NMR spectrometers are known from prior art. For example, U.S. Pat. No. 5,534,780 cited above has a sample changer with a vertical configuration. Here, NMR samples are released by a switching mechanism at a transfer position and mechanically conveyed into the magnet.
DE 10 2006 006 705 B4 describes details of a pneumatically operated sample changing apparatus for elongated NMR glass sample vials. Here, the glass sample vials are enclosed by a sample holder for immobilizing and transporting a glass sample vial, wherein the sample holder directly surrounds the NMR sample and moves with it into the measurement volume.
To be able to use large cost-intensive NMR spectrometers as economically as possible, the time it takes to change between different samples must be kept as short as possible. To achieve a high throughput of samples on NMR spectrometers, automatic sample changers are often used. On these conventional NMR spectrometers, samples are changed automatically by transferring a sample from a sample storage with a multiplicity of samples to a measuring location in the room temperature bore of the cryostat and back again.
However, in the case of smaller and more compact NMR spectrometers, NMR samples are usually loaded by hand, wherein, in particular, with NMR table-top devices, accessibility when transferring an NMR sample to the NMR spectrometer has so far been achieved in an ergonomically unfavorable manner. Due to the height and usual dimensions of the device, until now, samples had to be inserted vertically from above into a measurement volume in the region of the magnet. To do this, the person operating the device usually has to stretch his or her arm relatively far, which is strenuous and uncomfortable when samples are loaded and changed frequently.
The object of this invention is therefore to provide an ergonomically more favorable sample feed on an NMR spectrometer using suitable means.